This invention is directed generally to improvements in devices which generate X-Y co-ordinate information. Touch panels which respond to the interruption of intersecting light paths for developing data determinative of the X-Y position of the interruption are illustrative of the type of devices to which the invention is directed.
Conventional touch panels may include a CRT (Cathode Ray Tube) whose faceplate is surrounded by a plurality of discrete light emitting devices arranged to form intersecting light paths across the faceplate. Light sensors detect the interruption of a light path when a user touches a designated area of the CRT faceplate. In response to detecting such an interruption, the light sensors may output a signal to a controller for changing the display on the CRT faceplate. U.S. Pat. No. 4,247,767 exemplifies this type of display apparatus.
A significant problem associated with the conventional display device is the need for many discrete light emitting devices. In addition to their high cost and relatively poor resolution, the physical support for the light emitting devices and their wiring interconnects add additional expense. Furthermore, the usually uncertain reliability of the wiring interconnects renders such a display device impractical for many applications.
Accordingly, it is a general object of the invention to provide an improved X-Y co-ordinate detection system.
It is a more specific object of the invention to provide such a system which eliminates the need for a relatively large number of discreet light emitting devices.
It is another object of the invention to provide an improved system which utilizes a CRT faceplate for displaying graphics and one or more non-discrete emitters for developing X-Y co-ordinate interceptions on the CRT faceplate.